The Origin of Land Plants

DNA, structural, and biochemical evidence has conclusively pinpointed a particular group of freshwater green algae known as the charophyceans as the modern organisms that are most closely related to the earliest plants,
and have also revealed important steps in plant evolution. Bodies of the most basic charophyceans are either single-celled or form simple groups of cells. Other charophyceans more closely related to plants, according to DNA data, are more complex in their structure and reproduction. These include Coleochaete and Charales, a group that is commonly known as stoneworts. The comparison of simple to more complex charophyceans has revealed the origin of several important plant attributes, including: cellulose cell walls; intercellular connections known as plasmodesmata; and the phragmoplast, a specialized system of components necessary for plant cell division.

DNA evidence also marks liverworts as the modern land plants that appeared earliest; liverworts have...